The application is dividing an application of patent application case (denomination of invention being " semiconductor device, method, semi-conductor device manufacturing method, liquid crystal indicator and electronic equipment " for international filing date on March 30th, 2009, application number 200980111418.7).
Embodiment
Preferred exemplary embodiment below is described.
First exemplary embodiment
Below first exemplary embodiment is described in examination in the above-mentioned correlation technique.Fig. 1 is the view of the cross section structure of diagram semiconductor device (for example, thin-film transistor TFT) 10, and described semiconductor device is formed on the transparent support substrate 11, and this exemplary embodiment is suitable for described semiconductor device.
As supporting substrate 11, can be the glass substrate such as alkali-free glass or analog.Simultaneously, silicon dioxide film or comprise silicon nitride film and the laminated film of silicon dioxide film can be formed on the supporting layer 11 as the tape base film.
TFT10 is planar ransistor, and described planar ransistor comprises semiconductor film 12, gate insulating film 13, gate electrode 14 and source area 15a and drain region 15b, and described source area 15a and drain region 15b are formed on left side and the right side of gate electrode 14.
Low concentration region 17 is respectively formed between source area 15a and the channel formation region territory and between drain region 15b and channel formation region territory.Low concentration region has the impurity concentration less than the impurity concentration of the impurity concentration of source area 15a and drain region 15b.Source area 15a and drain region 15b are as being called as high concentration region 15 below the general name.The channel formation region territory is that raceway groove is formed on zone in the semiconductor film 12 below gate electrode 14 when operation of semiconductor devices.
Semiconductor film 12 forms by the polysilicon formation pattern that is formed in pairs on the supporting substrate 11.Gate insulating film 13 and gate electrode 14 are formed on the semiconductor film 12.In addition, by impurity element is injected in the semiconductor film 12 with ionic means, high concentration region 15 and low concentration region 17 form.
Semiconductor film is owing to the implanted dopant element is damaged, and the crystalline phase of described semiconductor film becomes amorphous.This phenomenon appears on the film, semiconductor film (polysilicon film) of patent documentation 2 propositions significantly.
In patent documentation 2, adopt single drain electrode structure, make leakage current flow through the crystal boundary of polysilicon film by the high electric field that is applied to the drain electrode side.Though this leakage current is penetrated along with illumination and increased, has higher value at the original leakage current of dark state current downflow.Because this, high brightness if perhaps reduce storage capacitance owing to making the LCD device have high resolution structures, then needs to reduce original dark state leakage current if desired.
Even because the implanted dopant element also deficiency be used for making the impurity element activation so that therefore himself function of impurity element performance after injecting, utilizes annealing that impurity element is handled.
As described in patent documentation 1, under transistor is formed on as the situation on the quartz base plate of supporting substrate, can adopt the high-temperature process that reaches about 1150 ℃.
Yet, needing greatly to reduce under the situation such as liquid crystal indicator of product cost, such as the glass substrate of cheap alkali-free glass, soda-lime glass or analog as supporting substrate.Can obtain liquid crystal indicator with very low cost by using cheap glass substrate.Because glass substrate is softened, therefore need in the K cryogenic treatment with the treatment temperature below softening temperature, handle described glass substrate under about 600 ℃.
Usually, treatment temperature is relevant with the activation degree that impurity injects, and further relevant with sheet resistance.If make the flowability of impurity infusion and activation grade be respectively μ and x, be approximately 10 at the product of μ and x
-1To 10
0K cryogenic treatment in, different greater than the high-temperature process of the product of the μ of K cryogenic treatment and x with the product of μ in the patent documentation 1 and x, the impurity infusion can not fully be activated, and makes that the resistance in the area with high mercury 15 can not be lowered.If the resistance in the area with high mercury 15 is higher, then the problem of Chan Shenging is when electric current flows through this zone, and a large amount of power are consumed, and the signal of this data wire accurately is applied to pixel electrode in the future.
Simultaneously, the technology of patent documentation 3 is controlled etch depth by selecting etching condition and impurity infusion along the CONCENTRATION DISTRIBUTION of the depth direction of semiconductor film.Even the advantage of this technology be when the thickness of semiconductor film hour, this technology also can be according to the degree of depth control etch depth of area with high mercury, thus the contact resistance that suppresses between interconnection and the area with high mercury increases.Yet this technology can not directly be contributed to the technical scheme that adopts K cryogenic treatment, because this technology has presupposed the low resistance of area with high mercury 15 and low concentration region 17.
Consider this, in order to realize the inhibition to the leak light electric current, the low resistance of the increase of the puncture voltage between source area and the drain region and area with high mercury 15 and low concentration region 17, exemplary embodiment can be included in structure B and the D among subsequently the structure A-E at least.In addition, exemplary embodiment can additionally only comprise other structure of another structure or merging form according to desired character.
Structure A
The light element of structure A use such as boron is as impurity element.By using this light impurity element, when the implanted dopant element, can reduce the amount of crystal defect.
Structure B
Structure B can make the thickness (t1) of semiconductor film have the scope of 20nm-40nm.When light incided on the semiconductor film, if the volume of semiconductor film 12 forms less (that is, forming thinner), the light-receiving volume reduced, and the minimizing of the quantity of the charge carrier that therefore is energized, and produced thereby suppress the leak light electric current.
Fig. 2 shows the correlation between the value of the thickness of semiconductor film when using silicon as semiconductor film 12 and standardization leak light electric current.The value of the electric current of standardization leak light simultaneously, is according to as the value of each film thickness being carried out standardized leak light electric current with reference to the value of the leak light electric current at the film thickness place of the 70nm of value.As being seen by Fig. 2, the value of standardization leak light electric current sharply reduces at 40nm or littler film thickness place.Therefore, the conclusion that can draw is that the upper limit of the thickness of semiconductor film 12 preferably can equal 40nm or littler.Simultaneously, from following reference structure E subsequently detailed described sheet resistance obtain the lower limit (20nm) of film thickness.
Structure C
Structure C is illustrated, make in the zone with certain depth scope of area with high mercury 15 on a side of supporting substrate 11 impurity concentration of (that is, in a side of supporting substrate 11 certain limit from the boundary face of semiconductor film 12 along thickness direction regional) be formed 3.4 * 10
20Cm
-3Or it is littler.Below, the zone that has certain limit from a side of supporting substrate will be called nearly substrate regions 18 (referring to Fig. 1).In this case, if basement membrane is present between supporting substrate 11 and the semiconductor film 12, nearly substrate regions is represented the zone with certain limit of the sensing from the border between basement membrane and the semiconductor film 12 along depth direction.The thickness (t2) of nearly substrate regions 18 can be preferably 0.6nm or bigger, more preferably is about 1nm or bigger.The thickness (t2) of nearly substrate regions can be preferably 1/4 times of thickness (t1) of semiconductor film 12 or littler.
Because area with high mercury 15 forms by the mode implanted dopant element with high concentration, so the degree of amorphous materialization is higher.Yet in K cryogenic treatment, noncrystalline semiconductor can not be by recrystallization easily.
It is the correlation at the some place of 40nm that Fig. 3 has shown between (boron) impurity concentration in the nearly substrate regions 18 and the sheet resistance at the film thickness when semiconductor film 12.
If impurity concentration surpasses 3.4 * 10
20Cm
-3, then can carry out the amorphous materialization of nearly substrate regions 18, but be not enough to implement the recovery from amorphous materialization to crystalline phase, make sheet resistance increase greatly.Simultaneously, if impurity concentration is no more than 3.4 * 10
20Cm
-3, then sheet resistance reduces greatly.
Simultaneously, if the phosphorus heavier than boron is used as impurity element, because the restriction that phosphorus is dissolved in the silicon is less, so sheet resistance increases.Therefore, the infusion that preferably is used for the nearly substrate regions 18 of semiconductor film 12 is phosphorus, and the concentration of described infusion equals 3.4 * 10
20Cm
-3Or it is littler.In fact, impurity concentration can be set at 3.4 * 10
20Cm
-3Or it is littler.
Therefore, be 3.4 * 10 by making the impurity concentration in the nearly substrate regions 18
20Cm
-3Or littler, then can reduce the degree of the semi-conductive amorphous materialization in the nearly substrate regions 18 that the injection by impurity obtains.That is, keep having not by the semiconductor of the crystalline phase of amorphous materialization.
Therefore, even in low-temperature activation annealing, the crystalloid semiconductor becomes the atomic nucleus for crystal growth, makes the easy crystallization of semiconductor of amorphous materialization.Crystallization allows to receive impurity in a side of silicon, rather than disperses (precipitating dispersion) as precipitation, thereby obtains low resistance.
Simultaneously, in order to obtain to add the abundant effect of impurity, the impurity concentration of area with high mercury 15 preferably can be 3.1 * 10
18Cm
-3Or it is bigger.In fact, impurity concentration can be set to 4 * 10
18Cm
-3Or it is bigger.
Structure D
Structure D provides low concentration region 17.When semiconductor film 12 forms when thinner, the reducing of the puncture voltage between source electrode and the drain electrode becomes remarkable.If the puncture voltage between source electrode and the drain electrode descends, then cut-off current increases.
The present inventor's latest find form the fact that significantly reduces of the puncture voltage between source electrode taking place and drain when thinner when the thickness (t1) of semiconductor film 12.Though theoretical foundation is unclear, the inventor supposes that this phenomenon is to be produced along the extension of thickness direction by the distribution of drain current when TFT10 is clamped.That is, thicker if the thickness of semiconductor film 12 (t1) forms, the depletion layer of the drain region when clamping can be broadened along thickness direction, and this makes that being difficult to produce electric field assembles.On the contrary, thinner if the thickness of semiconductor film 12 (t1) forms, depletion layer can not fully extend along thickness direction, makes to suppose that electric field is assembled generation also so puncture voltage reduces.
Therefore, low concentration region 17 is formed between raceway groove and the area with high mercury 15.Preferably low concentration region 17 is configured to have the CONCENTRATION DISTRIBUTION along thickness direction, make the impurity concentration of proximal border portion on a side of supporting substrate (near the lower surface of semiconductor film) form less than the impurity concentration in the proximal border portion (near the upper surface of semiconductor film) of a side of gate insulating film, thereby the resistance of the proximal border portion of a side of supporting substrate is higher than the resistance of proximal border portion of a side of gate insulating film.On the contrary, if the resistance of a side of supporting substrate less than the resistance of a side of gate insulating film, forms electric current at the boundary vicinity of a side of supporting substrate.When the proximal border portion in a side of supporting substrate forms higher resistance, make the boundary vicinity that is difficult in a side of supporting substrate form electric current.
Simultaneously, during from a side incident of supporting substrate, photocarrier produces by light stimulus at light.According to the optical absorption characteristics of semiconductor film, photocarrier further is created in a side of incidence surface.Here, if electric current is formed on the boundary vicinity of a side of gate insulating film, then the photocarrier that produces in a side of incidence surface (that is, in the proximal border portion part of a side of supporting substrate) is suppressed conveying, makes to suppress whole leak light electric current along thickness direction.
Fig. 4 is presented at the ratio of impurity concentration of nearly surface area in the low concentration region of semiconductor film 12 of TFT and nearly lower surface area (in the proximal border portion of a side of substrate) and the correlation between the standardization leak light electric current.Here, TFT is constructed such that the thickness of semiconductor film 12 has the scope of 20nm-40nm, and the impurity concentration of nearly substrate regions 18 equals 3.4 * 10
20Cm
-3Or still less.Axis of abscissas is represented standardization impurity concentration (Bs/Bb), wherein Bs is the impurity concentration of the nearly surface area (zone in the scope of distance upper surface 0-4nm) in the low concentration region of semiconductor film 12, and Bb is the impurity concentration of the nearly lower surface area (zone in the scope of distance lower surface 0-4nm) in the low concentration region of semiconductor film.Axis of ordinates is represented by by leak light electric current I p (1.79) leak light electric current I p is carried out the standardization leakage current [Ip/Ip (1.79)] that standardization obtains when standardization impurity concentration (Bs/Bb) is 1.79.
If standardization impurity concentration (Bs/Bb) becomes greater than 1, then the leak light electric current sharply reduces.Therefore, standardization impurity concentration (Bs/Bb) is formed to be larger than 1.That is, preferably in low concentration region 17, the impurity concentration of the proximal border portion of substrate one side (the nearly lower surface area of semiconductor film) is less than the impurity concentration of nearly surface area.
Structure E
Structure E makes the sheet resistance of low concentration region 17 have 3 * 10
5Ω/ to 2 * 10
7The scope of Ω/.
If semiconductor film 12 is polysilicon films, crystal boundary is present in the polysilicon film.Then owing to inhomogeneous defective in the crystal boundary, the cut-off current of TFT becomes inhomogeneous.Therefore, in liquid crystal indicator, need accurately to show and be used for keeping under the lower situation of the charge storaging capacitor of electromotive force of pixel electrode, the change in charge that keeps is owing to the inhomogeneous of the cut-off current of TFT becomes significantly, thereby makes picture quality produce inhomogeneities.
Fig. 5 shows the correlation between the ratio of the standardization standard deviation of cut-off current of the sheet resistance of low concentration region of semiconductor film and TFT and conduction and cut-off electric current.Here, the standardization standard deviation is to carry out standardized value by the highest standard deviation in the measured value shown in Fig. 5, and is used to indicate the index of the degree of irregularity of TFT product.Can be known that by Fig. 5 the standardization standard deviation of cut-off current can form by the sheet resistance that makes low concentration region and has 3 * 10
5Ω/ or bigger and fully suppressed.In addition, can also be known that if sheet resistance is higher and surpass 2 * 10 by Fig. 5
6Ω/ can obtain good homogeneous more.
Simultaneously, because the conducting electric current reduces when the sheet resistance of low concentration region increases, so the ratio of conduction and cut-off electric current diminishes, and makes the picture quality of liquid crystal indicator significantly worsen.Can be known that in order to ensure signal being write to the required minimum conducting electric current of pixel and the suitable ratio of conduction and cut-off electric current by Fig. 5, the sheet resistance of low concentration region be formed have 2 * 10
7Ω/ or littler.
By above-mentioned, the sheet resistance of low concentration region forms has 3 * 10
5Ω/ to 2 * 10
7The scope of Ω/, the feasible semiconductor device that can obtain fully to suppress the inhomogeneities of cut-off current.
More preferably the sheet resistance of low concentration region 17 is formed and has 3 * 10
5Ω/ to 1 * 10
6The scope of Ω/.It is to need sufficiently high conducting electric current in the TFT that need need driving force in peripheral drive circuit or analog that a kind of situation is arranged.Yet for the sheet resistance of low concentration region 17, if the conducting electric current of TFT increases, cut-off current also increases.Therefore the state that needs to suppress cut-off current and increase the conducting electric current.
The sheet resistance in Fig. 6 show lower concentration zone 17 and the correlation between conducting electric current or the cut-off current.As scheming as can be seen thus, can be set to 3 * 10 by the sheet resistance with low concentration region 17
5Ω/ to 1 * 10
6The scope of Ω/ obtains fully high conducting electric current simultaneously thereby fully suppress cut-off current.
Fig. 7 shows the correlation between the sheet resistance of the thickness of semiconductor film 12 and low concentration region 17.The figure shows the sheet resistance of the low concentration region 17 that in the TFT10 with semiconductor film 12, is injected into boron, and the varied in thickness of described semiconductor film.As seeing from Fig. 7, when the thickness of semiconductor film became thinner than 20nm, sheet resistance increased greatly.This is because when thickness reduces, and the soluble amount of solid of boron in semiconductor film 12 reduces.Therefore, be difficult to when film thickness is thinner than 20nm, reduce sheet resistance.
That is, in order to reduce sheet resistance, need make the thickness of semiconductor film 12 equal 20nm or bigger.Described thickness also can be set to 25nm or bigger.The thickness setting of semiconductor film 12 is being combined to 40nm or littler situation in structure B with above-mentioned, preferably equaling 20nm to the scope of 40nm thereby the conclusion that draws is the thickness of semiconductor film 12.
Therefore, can provide puncture voltage between a kind of source/drain higher and fully suppress the semiconductor device of leak light electric current.
Yet the required feature that is used for the TFT that uses together with pixel and the TFT that constitutes peripheral drive circuit is different usually.For example, as described above, the TFT of pixel needs the wide region uniformity, to suppress the inhomogeneities of display.Yet the TFT that uses in peripheral drive circuit needs higher driving force, because exist the occupied area that reduces peripheral drive circuit as small as possible so that the narrower needs of the width of the framework of liquid crystal indicator.Therefore, as described above, can form by the sheet resistance that makes low concentration region and have 3 * 10
5Ω/ to 2 * 10
7The scope of Ω/.In addition, in the TFT of the peripheral drive circuit that needs high driving ability or analog, can have 3 * 10 by the sheet resistance that makes low concentration region
5Ω/ to 1 * 10
6The scope of Ω/ satisfies the needs that obtain fully high conducting electric current.Therefore, can obtain the inhomogeneities that suppresses to show and exceed the less liquid crystal indicator in display part (so-called framework), and described liquid crystal indicator can promote high-quality display and miniaturization such as the electronic equipment of mobile phone or notebook PC.According to this exemplary embodiment, can provide the TFT that is suitable for this liquid crystal indicator.
Second exemplary embodiment
Following with reference to Fig. 8-10 explanation second exemplary embodiment.
Fig. 8 shows the cross section structure according to the semiconductor device 30 of second exemplary embodiment.Fig. 9 is the procedure chart that shows the example process of the method for making semiconductor device 30, and Figure 10 is the flow chart that shows the process of this method.
Semiconductor device (for example, TFT) 30 comprise basement membrane 32, semiconductor film 33, gate insulating film 34, gate electrode 35, insulating film of intermediate layer 36, source electrode distribution 37, drain electrode distribution 38 and analog, and described basement membrane 32, semiconductor film 33, gate insulating film 34, gate electrode 35, insulating film of intermediate layer 36, source electrode distribution 37, drain electrode distribution 38 and analog are formed on the supporting substrate 31.
In TFT30, between area with high mercury 40 (comprising source area 40a and drain region 40b) and raceway groove end, setting has the low concentration region 41 of low impurity concentration, thereby forms so-called lightly doped drain (LDD) structure.The impurity concentration of area with high mercury 40 has 3.1 * 10
18Cm
-3To 3.4 * 10
20Cm
-3Scope.In addition, the sheet resistance of low concentration region 41 is set to 3 * 10
5Ω/ to 1 * 10
6The scope of Ω/.
Below with exemplary fabrication the detailed construction of TFT is described.Manufacture process generally includes 6 processes.The reference symbol S1 corresponding with each process represents each step of the flow chart of Figure 10 to S2 simultaneously.
(1) semiconductor film forming process (S1)
At first, by silicon dioxide film or comprise silicon nitride film and basement membrane 32 that the laminated film of silicon dioxide film constitutes is formed on (referring to Fig. 9 (a)) on the supporting substrate 31.As supporting substrate 31, use the cheap glass substrate such as alkali-free glass or analog.
Approximately the amorphous materialization silicon fiml of 40nm is formed on the basement membrane 32 and (sees 9 (b)).Here, in order to control the threshold value of TFT30, during the film forming process with for example 1 * 10
16Cm
-3Dosage introduce impurity such as B or P.Simultaneously, after forming amorphous materialization silicon fiml, can inject by ion doping or ion and introduce impurity.
Then, the amorphous state silicon fiml is exposed to excimer laser or analog, thereby forms the semiconductor film with fabulous characteristic of semiconductor 33 of polycrystalline silicon.Semiconductor film 33 is etched into the pattern of expectation by photoetching process and dry etching method.
(2) gate electrode forming process (S2)
After forming semiconductor film 33, form gate insulating film 34 (referring to Fig. 9 (c)).In addition, as the preliminary treatment of gate insulating film forming process, semiconductor film 33 is processed into the hydrofluoric acid (DHF) that uses dilution and removes native oxide on the upper surface that is formed on described semiconductor film, thereby forms the silicon face of cleaning.
Gate insulating film 34 forms under the temperature below 600 ℃ by the plasma CVD method, and 600 ℃ temperature is lower than the temperature that makes supporting substrate 31 thermal deformations.The thickness of gate insulating film 34 equals but for example is not limited to preferred 5nm particularly to the scope of 5000nm, more preferably arrives 1000nm for 10nm.
Then, gate electrode film is formed on the gate insulating film 34.The silicon fiml that contains impurity that gate electrode film can obtain by the metal film that obtains by sputtering method, by CVD method or similar approach and comprise metal film and the laminated film of silicon fiml constitutes.Here, impurity for example can be B or P, and can introduce described impurity, changes concentration and the kind of impurity simultaneously, to regulate threshold value under the control of gate electrode 35 with respect to the work function of raceway groove end.
Use photoetching process that the photoresist pattern is formed on the gate electrode film, and the combination etching method etching grid electrode film of use dry etching, wet etching or described dry etching and described wet etching is to form gate electrode 35 (referring to Fig. 9 (d)).
(3) source area and drain region forming process (S3)
Before forming, low concentration region 41 forms the area with high mercury 40 of source area and drain region.Yet forming process can change, and makes at first to form low concentration region 41, forms corrosion-resisting pattern then with covering gate electrode 35 and low concentration region, thereby forms area with high mercury 40.Though this exemplary embodiment is presented at the situation that gate electrode 35 is carried out the formation of drain region and source region after forming, can implement forming process at first to form the mode that source area and drain region form gate electrode 35 then.
At first resist 50 is applied on the whole surface of semiconductor film, and forms the corrosion-resisting pattern (referring to Fig. 9 (e)) with opening 51 corresponding with area with high mercury 40.Inject the use corrosion-resisting pattern as the mode implanted dopant of mask with high concentration by ion doping or ion.After implanted dopant, remove corrosion-resisting pattern and finish the formation of area with high mercury 40.
In this process, preferably, impurity can be B.Here, can regulate the dosage of accelerating voltage and impurity, make the impurity concentration of nearly substrate regions equal 3.1 * 10
18Cm
-3To 3.4 * 10
20Cm
-3Scope.Thickness at semiconductor film 12 is under the situation of 40nm, silicon dioxide with film thickness of 160nm is formed on the described semiconductor film (in the gate insulating film side), then, uses ion doping to inject boron, can illustratedly be that accelerating voltage is 25keV, dosage be set to 6.7 * 10
15Cm
-2, and RF power is the condition of 100W.
Then, form low concentration region 41.Though the method for the method by being similar to area with high mercury 40 is carried out the injection of the impurity that is used to form low concentration region 41, does not use corrosion-resisting pattern, and gate electrode 35 is used as mask (referring to Fig. 9 (f)).
Here, accelerating voltage is configured to make the impurity concentration on the surface of a side of gate electrode 35 of semiconductor film to become than the impurity concentration height apparent surface's (lower surface) of a side of supporting substrate 12 at semiconductor film.In addition, adjusting dosage makes and has utilized the sheet resistance of the processed low concentration region of activation annealing process 41 preferably to equal 3 * 10
5Ω/ to 2 * 10
7Ω/ more preferably equals 3 * 10
5Ω/ to 1 * 10
6Ω/.
(4) insulating film of intermediate layer forming process (S4)
Next, form insulating film of intermediate layer 36.Insulating film of intermediate layer 36 forms silicon dioxide film, silicon nitride film or comprises that the lamination deposited film of described silicon dioxide film and silicon nitride film provides (referring to Fig. 9 (g)) by using plasma CVD to handle.
(5) activation annealing process (S5)
Next, carry out the activation annealing process with activated impurity infusion (referring to Fig. 9 (h)).Annealing temperature is set to 300 ℃ to 600 ℃ scope.Can or use such as the rapid method for annealing of excimer laser and carry out the activation annealing process in electric furnace.
(6) distribution forming process (S6)
After finishing the activation annealing process, contact hole 53 is formed in the insulating film of intermediate layer 36, and carries out the distribution forming process to form gate wirings, source electrode distribution and drain electrode distribution (referring to Fig. 9 (i) and Fig. 9 (j)).
By having with grid, source electrode and the opening corrosion-resisting pattern that drains corresponding in insulating film of intermediate layer 36 formation and using the combination etching insulating film of intermediate layer 36 of dry etching, wet etching or described dry etching and wet etching to form contact hole 53.After forming contact hole 53, use the metal film of sputtering method or similar approach formation such as aluminium film, and use dissimilar engraving methods and photoetching technique that metal film is etched with formation distribution 54.
In addition, preferably executive termination is arranged in the semiconductor film 33 or is arranged on the process of the borderline dangling bonds between semiconductor film 33 and the gate insulating film 34, with the stable electrical feature.The element that is used for stopping can be hydrogen.This termination can be that hydrogen plasma is handled.As long as after forming gate insulating film 34, can carry out this processing in any stage.
By said process, finished the main procedure of making TFT10.Under the situation that gate wirings and source electrode distribution or drain electrode distribution intersect (for example, be suitable at TFT under the situation of active matrix liquid crystal display apparatus), in order to arrange the distribution that intersects individually, can carry out the distribution forming process, simultaneously the distribution forming process is divided into two subprocess.
According to manufacture method, compare with correlation technique, under the situation that does not need some professional processes, create conditions by only arranging, the sheet resistance that can make low concentration region wherein is lower, the puncture voltage between source electrode and the drain electrode is higher and can fully suppress the leak light electric current, keep the adaptive semiconductor device of described process and correlation technique simultaneously.
The 3rd exemplary embodiment
Followingly describe the 3rd exemplary embodiment in detail with reference to accompanying drawing.Above-mentioned exemplary embodiment is carried out and operation such as the relevant inhibition leak light electric current of the structure of the semiconductor device of TFT10.The leak light electric current is produced by the charge carrier that is encouraged by incident ray.Light stimulus is to absorb the phenomenon that the incident ray charge carrier is excited in being with.Therefore, by reducing degree of absorption, even there is the crystal defect of same amount, also can reduce the leak light electric current.
Therefore, this exemplary embodiment suppresses the leak light electric current by the luminescent spectrum of restriction light source and the relation between the semi-conductive absorption spectrum.
Figure 11 shows the relative intensity spectrum of the luminescent spectrum of white light-emitting diode (LED) when maximum is set to 100, and Figure 12 shows the relative intensity spectrum when maximum is set to 1 of cold-cathode fluorescence lamp (CCFL).Like this, luminescent spectrum is based on light source and difference.Axis of ordinates is represented the relative value of luminous intensity.
Figure 13 shows the relative intensity spectrum when maximum is set to 1 of the absorption spectrum of three kinds of silicon fimls with different-thickness.Axis of ordinates is represented the relative value of absorption rate.
Correlation between the thickness of Figure 14 demonstration semiconductor film (silicon fiml) when light source is light-emitting diode and the integration of spectrum.
The integration of spectrum is to go up in total wave-length coverage (nm) A * B is carried out principal value of integral, wherein A (function of wavelength X: A (λ)) carries out standardization to the luminescent spectrum of each wavelength and the relative intensity spectrum that obtains with the maximum of the luminescent spectrum of light source, and B (function of wavelength X: B (λ)) carries out standardization to the absorption spectrum of each wavelength and the relative intensity that obtains is composed with the maximum of the absorption spectrum of semiconductor film.Here, total wave-length coverage can be that (λ min is to λ max, unit: nm) for the wave-length coverage that comprises the emission wavelength of light source.For example, when using visual ray as light source, wave-length coverage can be set to 380nm to 800nm or 400nm to 800nm.In addition, the maximum of the absorption spectrum of semiconductor film is illustrated in the interior maximum of emission wavelength scope of light source.
The integration of spectrum can be represented by following formula.In formula, λ max and λ min are illustrated respectively in maximum (nm) and the minimum value (nm) in total wave-length coverage.
Formula 1
Using under the situation of LED-backlit as light source as seen from Figure 14, the integration of spectrum is at the correlation on the film thickness and the correlation of leak light current characteristic on film thickness consistent (referring to Fig. 2).
It can be seen that the integration of spectrum increases with the minimizing of film thickness when film thickness is in 50nm arrives the scope of 70nm.This is that the peak value of the peak value of the luminous intensity of light source and the absorption characteristic of silicon fiml is overlapping because when film thickness is 50nm.Like this, the minimizing of leak light electric current is not to produce owing to the attenuation of silicon fiml simply, but is subjected to the influence of the correlation of the absorption characteristic of the luminescent spectrum of illumination light (LED-backlit) and semiconductor film (silicon fiml) and film thickness here here.In addition, if film thickness reduces, the integration of spectrum greatly changes near the film thickness of 40nm.That is, the integration of spectrum equal 5 or the thickness of littler semiconductor film be 40nm or littler.
As mentioned above, owing to absorbed wavelength exists based on film thickness, and because the correlation of luminescent spectrum (that is, luminous intensity) and wavelength exists based on the type of light source, so the scope of light absorption (so leak light electric current) is according to this changing features.The leak light current characteristic can be estimated by the integration of the spectrum of summarizing above-mentioned relation.In other words, from suppressing the point of leak light electric current, preferably the peak value of the absorption spectrum of the peak value of the luminescent spectrum of light source and semiconductor film almost can not be overlapped.Because this, the integration of spectrum is preferably 5 or littler, more preferably is 3 or littler.Because vanishing under the overlapping perfect condition of spectrum is not taking place the lower limit of the integration of spectrum, therefore, lower limit preferably surpasses zero.For the integration that makes spectrum has this scope, select the thickness of the type of light source and/or semiconductor film or comprise the material of particle diameter, density or analog.In addition, for a certain light source, select the thickness of semiconductor film or comprise the material of particle diameter, density or analog.Therefore, can obtain to suppress the semiconductor device of leak light electric current.
The 4th exemplary embodiment
Below go on to say the 4th exemplary embodiment.Exemplary embodiment provides a kind of liquid crystal indicator that has according to the semiconductor device of above-mentioned exemplary embodiment.Figure 15 is the concept exploded perspective view that shows liquid crystal indicator.
Liquid crystal indicator 55 comprises liquid crystal panel 56 and back light unit 57.Back light unit 57 comprises the light source such as cold-cathode fluorescence lamp, light-emitting diode or analog.Liquid crystal panel 56 comprises: a pair of supporting substrate 58a and 58b, supply liquid crystal 59 between described a pair of supporting substrate; Be arranged on data circuit 60, scanning circuit 61 and a viewing area 22 on the supporting substrate 58a; Be arranged on the common electrode (not shown) on another supporting substrate 58b; With the Polarizer (not shown) on the incidence surface that is arranged on liquid crystal panel 56 and the projection surface.
Data wire and scan line are connected to data circuit 60 and scanning circuit 61, make the viewing area 22 of liquid crystal panel 56 be divided into a plurality of pixels.
Data circuit 60 and scanning circuit 61 are provided with the semiconductor device of above-described embodiment, and each pixel also is provided with the semiconductor device of exemplary embodiment.
Therefore, according to the operation of said structure, even when the light from back light unit 57 incides on the semiconductor device in the liquid crystal panel 56, can suppress charge carrier and flow between source/drain as the leak light electric current, thereby avoid the reduction of picture quality, for example flicker.
In addition, by the low concentration region of structure D is provided, can suppress the reduction of the puncture voltage between source electrode and the drain electrode, thereby improve reliability.
In addition, because the sheet resistance of the area with high mercury of semiconductor device is enough low, even and when low concentration region was set, low concentration region had suitable sheet resistance, can reduce the power consumption of liquid crystal indicator.
In addition, because the integration of spectrum is owing to the relation with light source is set to 5 or littler, even therefore when using high brightness backlights unit 57, also can obtain fabulous display characteristic.
The 5th exemplary embodiment
Below go on to say the 5th exemplary embodiment.This exemplary embodiment relates to a kind of use according to the electronic equipment of the semiconductor device of above-mentioned exemplary embodiment.Though illustrated and illustrated the mobile phone with liquid crystal indicator as electronic equipment, but the invention is not restricted to this, but can comprise for example PC, PDA(Personal Digital Assistant), projecting apparatus, number (image) camera or analog.
Figure 16 is the stereogram that shows the mobile phone 65 with liquid crystal indicator.Mobile phone 65 comprises upper shell 66 and lower house 67.Upper shell 66 is provided with the liquid crystal indicator 69 according to above-mentioned exemplary embodiment, and lower house 67 is provided with the input unit that comprises numeric keypad.In addition, mobile phone also comprises the device with the required function of mobile phone in housing, and described device comprises transceiver, various controller, memory, has volume unit, battery and the analog of microphone and microphone.
Because liquid crystal indicator 69 suppresses leak light electric current and power consumptions, even therefore when using the high brightness backlights unit, also can provide long-term, fabulous relatively display characteristic, the feasible mobile phone that can obtain to have exceptional visibility.
In addition, in liquid crystal indicator of the present invention, can use this back light unit with high brightness, make described device be applicable to the good scene such as video camera that acquisition is in the dark used.
With reference to exemplary embodiment the present invention has been described so, but the present invention is not limited to above-mentioned exemplary embodiment.Can make structure of the present invention and details in protection scope of the present invention can be by the various modifications that those skilled in the art understood.
The application based on and advocate the benefit of priority of the Japanese patent application No.2008-096530 that on April 2nd, 2008 filed an application, the disclosure of this application is incorporated in full at this by reference.